Optical Pendulum

This unusual toy consists of a parabolic mirror with a small pendulum which hangs at the focal centre of the mirror. The Pendulum is spherical, and the front half is silvered, the rear half is red. Inside it contains a light bulb, and the little wire that suspends it is actually two wires, which supply the current to the bulb from the batteries in the base.

When you set the pendulum swinging, there is a moment when it is at the optical centre of the mirror, and the image of the pendulum appears to completely fill the main mirror. When the light bulb is switched on, the effect is even more dramatic.